What does an oil finish do to wood?

I am adding a shelf to the bottom of my work bench. While thinking about how to finish it, I started wondering about exactly what an oil finish (like BLO or Danish Oil) does to wood. Obviously, oil makes wood shiny, but what else does it do?

1) Does an oil finish harden the wood?2) Does it protect wood from abrasions, scuffs, or other mechanical damage?3) Does it protect wood from glue spills or other substances?4) Does it make the wood last longer?5) If I apply an oil finish only to the upper surface of a board, will the board warp?6) Does an oil finish stand up to heat (in a garage for example)?

Basically, if I’m going to go the trouble of finishing my entire bench with oil (except, maybe, the top), I want to make sure it’s worth the trouble and that it’s not going to blow up in my face some day (by being affected by hot temperatures, for example).

Thanks.

-- More tools, fewer machines.

6 replies so far

1) No2) No more than other finishes. The advantage of oil is that it penetrates the wood surface and does not have a layering like poly’s, lacquers, varnishes; so there is no chipping. Oiling makes for a much, much easier way to fix imperfections when they arise. Simply sand area appropriately and re-oil. Don’t forget to paste wax afterwards.3) It can. It is best to apply a paste wax after last oiling process is done.4) Yes, wood will generally last longer than other finishes due to its penetration. Of course like anything, it has to be done properly for best results.5) Possibly, I have had both happen…depends on wood, climate, etc. The best bet is to definitely oil both sides of the board.6) Yes, quite well. I posted my work bench http://lumberjocks.com/projects/37484 and I danish oiled it. It stays in my garage workshop all year and has never suffered any problems. The finish is still strong and durable. It has been over 2 years since I did it.

Oiling is my go- to finish on most things and I consider myself pretty savvy at it. There will be a lot of things to learn on the way but ultimately, you will come to love the results. One of many tips I can give is on your finer pieces, (not a work bench really) make sure you put a hand rub finish on. Once I feel the wood has pretty much absorbed several oilings, I hand rub the oil into the surfaces. Once dried, I steel wool and repeat, usually hand rubbing 2-3 times. After the last steel wooling I then apply the paste wax and hand rub thoroughly. Makes for a wonderful deep finish.Oiled wood cannot possibly blow up in your face. Dried oils are safe, wet oil is safe away from direct flame or spark. However your oiled rags will catch fire. The molecules in the oils and the rag start moving against each other, creating friction thus, spontaneous combustion. After using the oiled rag, rinse in water and store in an air tight container or dispose of immediately; even paper towels. Should be quite safe.So yeah, use the oil.

Also, it depends on what you mean by ‘oil finish’. If the product you are buying is an oil used as a finish, you’ll have different results than if you get an actual oil finish, which is likely to contain other additives like varnish. This is true for something like Danish Oil.

For the follow up question the answer is “no”, nothing does that. Consider and oil/varnish blend, it has the the advantages of oil and adds the durability of varnish, it is easily renewed if damaged, something likely on a workbench.

oil finish adds moisture protection to the wood – keeps moisture from sipping into the grain. will not necessarily protect from surface blemishes due to spills, but will prevent the liquids/moisture from getting into the wood and causing warps. and yes, this should minimize wood movement to some degree as less moisture can penetrate the wood

oil finish also keeps the wood from drying and splitting (not applicable in all cases, but it does that nonetheless)